Re: Problem with scoping a variable value

> Hi there,
>
> I have a function which has a variable called show as an input:
>
> richardson.grad <- function(func, x, d=0.01, eps=1e-4, r=6, show=F){
> # do some things
> if(show) {
>
> cat("\n","first order approximations", "\n")
> print(a.mtr, 12)
>
>
> }
> #do more things and return
> }
>
> The show variable is being used as a flag to show intermediate results.
>
> Interestingly enough, I have downloaded a package recently which defines
> the show variable as a function:
>
> > show
> standardGeneric for "show" defined from package "methods"
>
> function (object)
> standardGeneric("show")
> <environment: 01676F7C>
> Methods may be defined for arguments: object
>
> >
>
> Now, all of a sudden, the function I had defined earlier is scoping up
> to this new value, and is thus not working:
>
> > richardson.grad(function(x) x^2,2)
> Error in if (show) { : argument is not interpretable as logical
> >
>
> I could always redefine show in richardson.grad to be something else but
> something seems wrong: why is richardson.grad not looking up show's
> value in the function ? How would I fix this ?
>
> Thanks in advance,
> Tolga
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html>

Re: Problem with scoping a variable value

> I have a function which has a variable called show as an input:
>
> richardson.grad <- function(func, x, d=0.01, eps=1e-4, r=6, show=F){
> # do some things
> if(show) {
>
> cat("\n","first order approximations", "\n")
> print(a.mtr, 12)
>
>
> }
> #do more things and return
> }
>
> The show variable is being used as a flag to show intermediate results.
>
> Interestingly enough, I have downloaded a package recently which defines
> the show variable as a function:
>
> > show
> standardGeneric for "show" defined from package "methods"
>
> function (object)
> standardGeneric("show")
> <environment: 01676F7C>
> Methods may be defined for arguments: object
>
> >
>
> Now, all of a sudden, the function I had defined earlier is scoping up
> to this new value, and is thus not working:
>
> > richardson.grad(function(x) x^2,2)
> Error in if (show) { : argument is not interpretable as logical
> >
>
> I could always redefine show in richardson.grad to be something else but
> something seems wrong: why is richardson.grad not looking up show's
> value in the function ? How would I fix this ?

You didn't spell out the logical value 'FALSE' which may
be causing your problem. Consider this alternative also...

> Hi there,
>
> I have a function which has a variable called show as an input:
>
> richardson.grad <- function(func, x, d=0.01, eps=1e-4, r=6, show=F){
> # do some things
> if(show) {
>
> cat("\n","first order approximations", "\n")
> print(a.mtr, 12)
>
>
> }
> #do more things and return
> }
>
> The show variable is being used as a flag to show intermediate results.
>
> Interestingly enough, I have downloaded a package recently which defines
> the show variable as a function:
>
> > show
> standardGeneric for "show" defined from package "methods"
>
> function (object)
> standardGeneric("show")
> <environment: 01676F7C>
> Methods may be defined for arguments: object
>
> >
>
> Now, all of a sudden, the function I had defined earlier is scoping up
> to this new value, and is thus not working:
>
> > richardson.grad(function(x) x^2,2)
> Error in if (show) { : argument is not interpretable as logical
> >
>
> I could always redefine show in richardson.grad to be something else but
> something seems wrong: why is richardson.grad not looking up show's
> value in the function ? How would I fix this ?
>
> Thanks in advance,
> Tolga
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide!

Re: Problem with scoping a variable value

> On Thu, 16 Feb 2006, Tolga Uzuner wrote:
>
>
>>I have a function which has a variable called show as an input:
>>
>>richardson.grad <- function(func, x, d=0.01, eps=1e-4, r=6, show=F){
>># do some things
>> if(show) {
>>
>> cat("\n","first order approximations", "\n")
>> print(a.mtr, 12)
>>
>>
>> }
>>#do more things and return
>>}
>>
>>The show variable is being used as a flag to show intermediate results.
>>
>>Interestingly enough, I have downloaded a package recently which defines
>>the show variable as a function:
>>
>> > show
>>standardGeneric for "show" defined from package "methods"
>>
>>function (object)
>>standardGeneric("show")
>><environment: 01676F7C>
>>Methods may be defined for arguments: object
>>
>> >
>>
>>Now, all of a sudden, the function I had defined earlier is scoping up
>>to this new value, and is thus not working:
>>
>> > richardson.grad(function(x) x^2,2)
>>Error in if (show) { : argument is not interpretable as logical
>> >
>>
>>I could always redefine show in richardson.grad to be something else but
>>something seems wrong: why is richardson.grad not looking up show's
>>value in the function ? How would I fix this ?
>
>
> You didn't spell out the logical value 'FALSE' which may
> be causing your problem. Consider this alternative also...
>
> richardson.grad <- function(func,
> x,
> d = 0.01,
> eps = 1e-4,
> r = 6,
> verbose = getOption("verbose")) {
> ## do some things
> if (verbose) {
> cat("\n", "first order approximations:", "\n")
> print(a.mtr, 12)
> }
> ## do more things and return
> }

This is definitely the best solution, and Paul is right: you have to use
FALSE in preference to F (FALSE is a reserved word, F is not in R).

Now, you should know that show() *is* a generic function (it is the
default method for S4 objects), and it is a very bad idea to use it as
named argument for functions. I would suggest to use Paul's suggestion
instead, or to change it as 'show.it = FALSE', as a minimum.
Best,